Lamp for projecting apparatus



April 15, 1930. UHLEMANN 1,754,658

LAMP FOR PROJEGTING APPARATUS Original Filed Nov. 3, 1920 2 Sheefs-Sheet l ATTORNEY April 15, 1930. T. F. UHLEMANN LAMP FOR PROJECTING APPARATUS Original Filed Nov. 3, 1920 2 Sheets-Sheet 2 INVENTOR BY v d/z/luwm Patented Apr. 15, 1930 UNITED STATES PATENT oFncE THEODORE F. UHLEMANN, OF GLEN MORRIS, NEW YORK, ASSIGNOR TO NICHOLAS POWER COMPANY, INC., NEW YORK, N. Y., A CORPORATION OF DELAWARE LAMP FOR PROJECTTNG APPARATUS Original application filed November 3, 1920, Serial No. 393,602. Divided and this application filed 23, 1924. Serial No. 733,703.

This invention relates to lamps for projecting apparatus particularly incandescent electric lam s.

This application is a division of my U. S. application, Serial No. 393,602, filed July 2, 1920 and now U. S. Patent No. 1,507,095.

It is an object of the invention to provide a lamp of this character in which the socket for the light bulb is readily detachable from its adjustable base forming part of the lamp proper. By this arrangement a number of interchangeable lamp sockets may be provided in each of which a bulb will be set before the exhibition begins, so that a fresh bulb may be substituted in case the one in use burns out, with only a momentary interruption of the exhibition.

It is a further object to provide a lamp for motion picture projectors and a socket and support for the lamp of such nature that the lamp may be brought into operative relation with the current supplying contacts of the socket over a reasonably wide range of loca tion. By this arrangement, it is always possible to position the lamp filament properly with respect to the optical system of the projector and at the same time secure adequate contact with the current supplying terminals of the socket.

My invention also contemplates various improvements in the detachable socket and the electrical connections therefor, which improvements will be more readily understood from the following description and appended claims.

In the accompanying drawings, I have illustrated my invention applied to a lamp adapted primarily for the projection of motion pictures.

Figure 1 is a sectional view on an enlarged scale of the detachable bulb socket;

Figure 2 is an elevational view of the socket looking from the right of Figure 1;

Figure 3 is a detail sectional view through one of the contacts of the bulb socket;

Fig. 3 is a sectional View on line 33 of Fig. 1;

Figure 4 is a diagrammatic view showing the relative positions of the real filament and its reflection;

August Figures 5 and 6 are detail views of a modification and Fig. 7 is a perspective view of the form shown in Fig. 1, and its electrical circuit lines.

Incandescent lamps for projecting apparatus as now commonly manufactured have the filament arranged in a series of short coils arranged vertically in parallelism in a single transverse plane, the spaces between the in dividual coils of the light being about equal to the diameter of the coils, whereby with a proper reflector the images of the several filaments may be reflected into the spaces between the actual filaments. The light proj ected through the condensers is thus in effect a spot of light equal to the filaments and their intervening spaces and of substantially uniform intensity throughout. The arrangement of the filament and the reflector is illustrated diagrammatically in Fig, 4, wherein the solid lines indicate the actual filaments and the dotted lines 21 the reflected images.

To secure proper reflection of the filament it is necessary that the bulbs be set in their sockets so that the plane of the filaments lies transversely of the optical axis of the reflector and the condensers, and it is not feasible in manufacture to maintain a definite relation between the threads on the neck of the bulb and the position of the filament. The bulb cannot always be screwed tight into the socket, but must be stopped with the plane of the filament transverse of the optical axis, even though it would require a quarter turn or more of the bulb to bring the lamp contact hard against the base of the socket.

It has been proposed to employ spring contacts in lamp sockets for projection apparatus, after the fashion of ordinary lighting bulb sockets, to maintain the contact in different positions of adjustment of the bulb, but such lamps require high candle power and such contacts have not been found altogether satisfactory for electric current of the high amperage required. I have therefore devised, as part of my invention, a novel form of lamp socket in which a contact actuated by positive pressure as distinguished from a spring contact of the ordinary lighting socket type is provided for establishing an electrical connection to the end-of the lamp bulb in various positions in the lamp socket. The lam socket proper is also made detachable rorn the base of the lamp-sup orting bracket so that interchan eable amp sockets with pre-ad'usted bulbs in them may be provided in or er to rapidly renew the burned out lam My improved lamp socket comprises a base plate 40 adapted to be fixedly attached to the lamp supporting bracket by a central screw or in any other convenient manner. This base plate is preferably made of compressed fibre, vulcanite, or some other suitable insulating material. The upper face of the late 40 is cut away in the manner shown in ig. 2 to receive from one end a detachable socket supporting base plate 41, the plate 41 being maintained in pos1tion on the base plate 40 b a latch 42 which holds the tapered forwar end of the plate 41 against correspondingly inclined faces of the side flanges 44 of the plate 40, the side flanges being undercut as shown in Figure 2 to overlap the similarly inclined edges of the late 41 to hold the two plates against vertica separation.

The plate 41 is also formed of insulating material and is preferably integral with the lamp socket 45 in which is supported the standard threaded metal sleeve 46 into which the bulb is screwed. The sleeve 46 has its bottom edge on one side turned in as sho wn at 47 in Fig. 1, this edge being clamped against the base of the socket by a metal contact iece 48 of the shape shown in Fig. 1, which piece extends through the vertical wall of the socket across the face of the plate 41 and is turned down at the end in position to be'clamped against the upturned end of the leading-in contact 49 attached to the base late 40 in the manner shown particularly in Figure 3.

The late 40 is also provided with a similar lea in -in contact 50 for the other terminal of the ight circuit, which is turned down over the ed of the piece 41 in the same manner as t z plate 48. The contact 50 cooperates with a metal conductor 51 which, as shown in Figure 1, is provided with a spring tongue 52 projecting through an opening in the side of the sleeve 46 in position to lie under and enga e the center contact of the bulb when the bul is screwed into the sleeve 46.

The contact 51 is separated from the contact 48 by a ridge 53 of insulating material on the bottom of the socket 45 and lying within a recess formed within the ridge under the tongue 52 is an L-shaped piece 54 of stiff metal adapted to be pressed against the under side of the spring tongue 52 after the bulb is adjusted in the socket to insure a good electrical contact between the tongue and the bulb.

As shown in Fig. 1, the piece 54 has its short end projecting downwardly into a recess 55 cut in the bottom of the socket 45, the edge of the recess which lies in the angle of the piece 54 being undercut as shown, so that w en pressure is applied to the outer face of the short end of the piece 54 the edge of the recess will serve as a fulcrum and cause the long end of the piece to be tilted up against the bottom of the spring and press it into contact with the lamp terminal. The pressure is preferably applied to the end of the piece 54 by a thumb screw 56 threaded through a block 80 set in the base 41.

The socket 45 is provided on the side away from the adjusting screw 56 with a handle 80, and adjacent the handle 80 the latch 42 is arranged so that the thumb piece 58 formmg the upper part of the latch may be readily held by the thumb of the operator when the handle is grasped. The latch 42 is pivoted on a stud 59 set in the side of the socket 45, the latch being held between a shoulder on the stud and the shouldered screw 60 threaded in the stud, in the manner shown in Figure 1. A spring 61 is coiled around the shoulder of the screw with its free end engaging the latch in a direction such that the spring holds the free end of the latch in engagement with the hook 62 set in the base 40.

In using my improved lamp socket, the socket 45 will be set in position on the plate 40, thereby connecting the sleeve 46 and spring contact 52 with the opposite terminals of the electric circuit through the conductors 49 and 50 whose resilient upturned ends preferably project somewhat beyond the face of the insulation as shown in Figure 3 to insure a good contact when the plate 41 is latched in place. The bulb will then be screwed into the sleeve 46 until its end is in good contact with the spring 52 so that when the current is turned on the lamp will be lighted and the operator can turn the bulb in the socket one way or the other, as may become necessary to get the filaments adjusted in a plane exactly transverse of the optical axis, which may be determined by the projection of the filament on the light shield of the projection apparatus. After the lamp is properly positioned the contact piece 54 will be clamped against the under side of the tongue 52 by means of the screw 56, thereby clamping the bulb rigidly in its adjusted position and atthe same time holding the contact members in firm engagement.

Before the exhibition the operator will properly adjust two bulbs in interchangeable sockets so that in case one burns out during the exhibition it may be quickly removed by merely releasing the latch 42 and putting the other in place. The adjustment of the second bulb and the reflector may then be slightly altered as necessary by means of the adjusting screws to correct the slight differences in the positioning of the filaments with respect to the threaded ends of the bulbs. The exhibition need not be delayed while this adjustment is being made, however, for the reason that if the filaments are properly adjusted in a transverse plane there will be suiticient light, even though slightly out of focus, for the projection of the picture. In fact, the dilference in intensity between-the incandescent light when slightly out of focus and when properly positioned is no greater than the unavoida le variations in the inten sity of the hand trimmed arclight as now almost universally employed in motion picture apparatus.

In Figs. 5 and 6 I have illustrated a slightly modified apparatus wherein a sliding contact between the lamp base and the lamp socket is obtained in lieu of the pressure contacts employed in the above described construction. To this end, the base 40 is provided at its edges with side flanges 42 between which the base 41 may be inserted from one side. At the ends of the side flanges 42 away from the handle of the socket, contact pieces are embedded in the fibre of the base with their side edges upturned and set in recesses in the faces of the flanges 42 and flush with the faces of the flanges, as indicated at 71 in Figure 6. As shown in Figure 6, the contacts comprise projecting terminals for the attachment of the electrical conductors and stops 72 for the detachable socket plate 41, the stop 72 being formed by turning up projecting pins of the contact plates in the manner shown. Except for the stops and terminals the surface of the contacts is flush throughout with the adjacent faceof the fibre so that the base 41 may he slid into the base until its edge comes in contact with the stops. The flanges 42 need not be undercut as in the previously described construction, but instead the stops 72 are turned in to engage over the beveled edge of the base 41. and the latch 42 will be constructed to catch under the hook 62 to hold the socket firmly in the base.

For cooperation with the contact plate 71 the base 41 is provided at corresponding corners with spring tongues 73, 74, respectively, each of which consists of a plate of spring metal attached to the upper surface of the base plate 41 with its outer end turned down in a recess formed in the corner of the base plate and bent back upon itself in a loop, as shown at 74, the outer portion of the loop contacting with the part 71 when the socket is in place.

The spring tongue 52 is attached to the socket plece over the fixed part of the contact 73 to conduct the current to the inner terminal of the lamp bulb while the other contact 74 is similarly connected to the contact strip 48, which in turn is connected to the lamp socket in the manner already described. The socket disclosed in Figs. 5 and 6 is also provided with the clamping piece 54-and screw 56 whereby the bulb may be firmly secured in place when properly adjusted. j j

The above described socket is in all respects the equivalent of the previously described structure and represents one of the many Ways in which the design may be modified, as will be readily understood by those skilled in the art. a

I claim:

1. Apparatus of the class described comprising a base for supporting the lamp is operative position in the projector, a carrying member dctachably associated with said base, a socket for the projecting lamp mounted on said carrying member, a terminal within said socket for making contact with the base of the lamp and means external to said terminal and having a variable length projecting into said socket for positively forcing said terminal into contact with the lamp base.

2. Apparatus of the class described, com- I prising a base for supporting the lamp in operative position in the projector, a carrying member detachably associated with said base, a socket for the projecting lamp mounted in said carrying member, means extending from the outside of the apparatus through the socket for contacting with the base of the lamp, and means extending into said socket for regulating the pressure between said contact means and the base of the lamp.

3. Apparatus of the class described con1- prising a base for supporting the lamp in operative position in the projector, a carrying member detachably associated with said base, a socket for the projecting lamp mounted on said carrying member, a terminal within said socket for making contact with the base of the lamp notwithstanding adjustment of said lamp to difierent positions in the socket, means external to said terminal for positively forcing said terminal into contact with the lamp base and means on the outside of the apparatus for regulating and setting the pressurebetween said contact. terminal and the base of the lamp.

4. Apparatus of the class described, comprising a base for supporting the lamp in operative position in the projector, a carrying member detachably associated with said base, a socket for the projecting lamp mounted in said carrying member, means extending from the outside of the apparatus through the socket for contacting with the base of the lamp, a loose member seated in said socket below said contact means, and means extending into said socket for regulating the pressure between said contact means and the base of the lamp.

5. Apparatus of the class described, comprising a base for supporting the lamp in operative position in the projector, a carry ing member detachably associated with said base, a socket for the projecting lamp mount ed in said carrying member, means extending within the socket from the outside of the apparatus through the socket for contacting with the base of the lamp, a member seated in said socket below said contact means, and another member extending into said socket and projecting into juxtaposition with said seated member for raising said member into contact with said contact means to thereby provide a set but regulable pressure between said contact means and the base of the lamp over a wide range of adjustment thereof.

(3. Apparatus of the class described, comprising a base for supporting a lamp in operative position in a projector, a separate -arr \'ing member for the lamp slidably associated with said base, said member having a hollow center and a lamp socket therein above said center, a strip of conducting material extending from the front edge of said carrying member into said socket and engaging over one edge of the socket, another strip of conducting material extending from the edge of said carrying member into said socket and over the hollow center, a lever-member seated in said hollow center beneath said conducting material,'and a variable-setting member extending from the exterior face of said carrying member into contact with said lever-member for positively forcing said lever into contact with said second conducting material to complete the circuit through the lamp over a wide range of adjustments of the lamp in the socket.

7. Apparatus of the class described, comprising a base for supporting a lamp in operative position in a projector, a separate carrying member for the lamp, said base having a closed end and an open end and engaging by its sides over said carrying member, said member being seated against the end of said base. said carrying member having a lampsocket therein and having a hollow beneath said socket, said socket having its bottom edge on one side thereof turned inwardly, a strip of conducting material fitted over said edge and extending outwardly over said carrying member, the other terminal for the lamp comprising another strip of conducting-material extending from the outside of said carrying member into the hollow portion thereof a lever member seated in said hollow portion, and an adjustable member set in the outside of said carrying member and extending into contact with said lever-member for positively forcing said lever into contact with said con ducting material to complete the lamp circuit over a wide range of positions of the lamp.

In testimony whereof I aflix my signature.

THEODORE F. UHLEMANN. 

